Added checking for missing return type in alternative signature.

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/AlternativeSignatureParsing.java

@@ -156,6 +156,26 @@ class AlternativeSignatureParsing {
         return result;
     }
 
+    static JetType computeAlternativeReturnType(@NotNull JetType autoType, @Nullable JetTypeReference altReturnTypeRef)
+            throws AlternativeSignatureMismatchException {
+        JetType altReturnType;
+        if (altReturnTypeRef == null) {
+            if (JetStandardClasses.isUnit(autoType)) {
+                altReturnType = autoType;
+            }
+            else {
+                throw new AlternativeSignatureMismatchException(String.format(
+                        "Return type in alternative signature is missing, while in real signature it is '%s'",
+                        DescriptorRenderer.TEXT.renderType(autoType)));
+            }
+        }
+        else {
+            altReturnType = computeAlternativeTypeFromAnnotation(altReturnTypeRef.getTypeElement(),
+                                                                 autoType);
+        }
+        return altReturnType;
+    }
+
     static JavaDescriptorResolver.ValueParameterDescriptors computeAlternativeValueParameters(
             JavaDescriptorResolver.ValueParameterDescriptors valueParameterDescriptors,
             JetNamedFunction altFunDeclaration) throws AlternativeSignatureMismatchException {

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java

@@ -1400,11 +1400,8 @@ public class JavaDescriptorResolver implements DependencyClassByQualifiedNameRes
 
                 ValueParameterDescriptors altValueParameters = AlternativeSignatureParsing
                         .computeAlternativeValueParameters(valueParameterDescriptors, altFunDeclaration);
-                JetTypeReference returnTypeRef = altFunDeclaration.getReturnTypeRef();
-                JetType altReturnType = returnTypeRef != null
-                                        ? AlternativeSignatureParsing.computeAlternativeTypeFromAnnotation(returnTypeRef.getTypeElement(),
-                                                                                                           returnType)
-                                        : returnType;
+                JetType altReturnType = AlternativeSignatureParsing.computeAlternativeReturnType(returnType,
+                                                                                                 altFunDeclaration.getReturnTypeRef());
                 List<TypeParameterDescriptor> altTypeParameters = AlternativeSignatureParsing
                         .computeAlternativeTypeParameters(methodTypeParameters, altFunDeclaration);
                 // if no exceptions were thrown, save alternative data

compiler/testData/readJavaBinaryClass/kotlinSignature/error/ReturnTypeMissing.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2010-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package test;
+
+import jet.runtime.typeinfo.KotlinSignature;
+
+import java.lang.String;
+
+public class ReturnTypeMissing {
+    @KotlinSignature("fun foo(a : String)")
+    public int foo(String a) {
+        throw new UnsupportedOperationException();
+    }
+}

compiler/testData/readJavaBinaryClass/kotlinSignature/error/ReturnTypeMissing.kt

@@ -0,0 +1,9 @@
+package test
+
+import java.util.*
+
+public open class ReturnTypeMissing : Object() {
+    public open fun foo(p0 : String?) : Int {
+        throw UnsupportedOperationException()
+    }
+}

compiler/testData/readJavaBinaryClass/kotlinSignature/error/ReturnTypeMissing.txt

@@ -0,0 +1,6 @@
+namespace test
+
+public open class test.ReturnTypeMissing : java.lang.Object {
+    public final /*constructor*/ fun <init>(): test.ReturnTypeMissing
+    public open fun foo(/*0*/ p0: jet.String?): jet.Int
+}